Optical sensor and method of manufacture

Abstract

An exemplary embodiment of the present invention provides an optical sensor, including: a substrate; an infrared ray sensing thin film transistor including a first semiconductor layer that is formed on the substrate and arranged to operate by receiving infrared light, and a bandpass filter formed on the substrate and sized and arranged to pass the infrared light; a visible ray sensing thin film transistor including a second semiconductor layer formed on the substrate and arranged to operate by receiving visible light; and a switching thin film transistor including a third semiconductor layer formed on the substrate, wherein the bandpass filter may be formed of a metal material patterned to have features, successive features spaced apart from each other by a predetermined period so as to pass the infrared light and to block the visible light.

What is claimed is: 
     
       1. An optical sensor, comprising:
 a substrate; 
 an infrared ray sensing thin film transistor including a first semiconductor layer over the substrate so that the infrared ray sensing thin film transistor is arranged to operate by receiving infrared light, and a bandpass filter formed on the substrate and sized and arranged to pass the infrared light; 
 a visible ray sensing thin film transistor including a second semiconductor layer over the substrate so that the visible ray sensing thin film transistor is arranged to operate by receiving visible light; and 
 a switching thin film transistor including a third semiconductor layer and a lower gate electrode overlapping the third semiconductor layer over the substrate 
 wherein the bandpass filter comprises a patterned metal material, patterns of the metal material of the bandpass filter are spaced apart from each other by a predetermined period to block the visible light, and the lower gate electrode comprises the same metal material and is at the same layer as the bandpass filter; and 
 wherein the infrared ray sensing thin film transistor further comprises:
 a first source electrode and a first drain electrode formed over the first semiconductor layer; 
 an insulating layer over the first source electrode and the first drain electrode and at least a portion of the metal material of the bandpass filter, the insulating layer having a contact hole on the metal material of the bandpass filter; and 
 a first upper gate electrode over the insulating layer is connected directly to the metal material of the bandpass filter through the contact hole. 
 
 
     
     
       2. The optical sensor of  claim 1 , wherein
 the bandpass filter comprises holes formed in the metal material. 
 
     
     
       3. The optical sensor of  claim 2 , wherein
 the metal material comprises at least one among aluminum, molybdenum, copper, gold, silver, or chromium, 
 a shape of a hole of the holes is one of a circle, a quadrangle, a polygon, and a slit, and 
 adjacent holes are spaced apart from each other by the predetermined period, the predetermined period having a length of about 390 nm to about 460 nm. 
 
     
     
       4. The optical sensor of  claim 1 , wherein
 the bandpass filter comprises metal particles. 
 
     
     
       5. The optical sensor of  claim 4 , wherein
 the metal particles comprise at least one among aluminum, molybdenum, copper, gold, silver, and chromium, 
 a shape of a metal particle of the metal particles is one of a circle, a square, and a rectangle, and 
 adjacent metal particles are spaced apart from each other by about 390 nm to about 460 nm. 
 
     
     
       6. The optical sensor of  claim 1 , wherein
 the first semiconductor layer includes amorphous silicon germanium. 
 
     
     
       7. The optical sensor of  claim 1 , wherein the infrared ray sensing thin film transistor further includes:
 an ohmic contact layer between the first semiconductor layer and at least one of the first source electrode and the first drain electrode. 
 
     
     
       8. The optical sensor of  claim 1 , wherein
 the second semiconductor layer and the third semiconductor layer include amorphous silicon. 
 
     
     
       9. The optical sensor of  claim 1 , wherein the visible ray sensing thin film transistor includes:
 an ohmic contact layer over the second semiconductor layer; 
 a second source electrode and a second drain electrode over the ohmic contact layer; 
 the insulating layer over the second source electrode and the second drain electrode; and 
 a second upper gate electrode over the insulating layer. 
 
     
     
       10. The optical sensor of  claim 1 , wherein the switching thin film transistor includes:
 a first insulating layer over the lower gate electrode; 
 an ohmic contact layer over the third semiconductor layer; 
 a third source electrode and a third drain electrode over the ohmic contact layer; 
 a second insulating layer over the third source electrode and the third drain electrode; and 
 a third upper gate electrode over the second insulating layer.